This invention relates in general to power monitoring equipment and in particular to an improved method and apparatus for deriving power consumption data from power meters.
Power generating companies often have a need to monitor the consumption rate of individual users. This information may be used for predicting future demand loads, for automatic billing purposes, or for a number of other reasons. There are devices now made that may be installed in power meters, usually electric meters, that will monitor the consumption rate and produce a serial pulse train indicating the rate of usage. These devices, often called pulse initiators, are made by the same companies that manufacture the power meters, and are usually tailored to operate only in conjunction with the meters made by that company.
Generally there are two different techniques used for monitoring consumption from a power meter and to generate pulses therefrom. The first uses a gearing mechanism driven from a rotating gear shaft in the power meter. The second obtains pulses from the rotor (i.e. the rotating disc in the meter by: (1) interruption of an optical signal, (2) interruption of a capacitive coupling mechanism connected in some manner to the rotor, or by (3) reflection of an optical signal. Types (1) and (2) require a special type of rotor which has holes located at strategic locations. This type of design can by used only by manufacturers of power meters since it has to be incorporated in the meters at the manufacturing stage of the product.
Type (3) requires non-reflective stripes or areas to be present on the rotor. Since non-reflective tape or paint is easily added to rotors in existing meters this technique is more universal in nature. Notwithstanding, because of the large variety of meters that have been made and are still in use, there is no single pulse initiator device that will operate reliabily in even most of these power meters now in use. Such devices are also very expensive, at times unreliable, and often cost more than the power meter itself.